DHCP issue with NetworkManager (fairphone-fp2)

(copied from #148 (closed)) Even with #50 (closed) fixed, using NetworkManager doesn't work without further configuration on fairphone-fp2.

Mar 10 12:00:42 fairphone-fp2 daemon.info NetworkManager[1631]: <info>  [1552215642.8512] device (wlan0): state change: config -> ip-config (reason 'none', sys-iface-state: 'managed')     
Mar 10 12:00:42 fairphone-fp2 daemon.info NetworkManager[1631]: <info>  [1552215642.8529] dhcp4 (wlan0): activation: beginning transaction (timeout in 45 seconds)                          
Mar 10 12:00:42 fairphone-fp2 daemon.warn NetworkManager[1631]: <warn>  [1552215642.8737] dhcp4 (wlan0): unhandled DHCP event -22                                                           
Mar 10 12:00:42 fairphone-fp2 daemon.warn NetworkManager[1631]: <warn>  [1552215642.8738] dhcp4 (wlan0): failed to start client (-22)                                                       
Mar 10 12:00:42 fairphone-fp2 daemon.info NetworkManager[1631]: <info>  [1552215642.8740] device (wlan0): state change: ip-config -> failed (reason 'dhcp-start-failed', sys-iface-state: 'managed')

I was able to connect to the WiFi by editing the connection in nmtui setting IPv4 / IPv6 configuration to Disabled/Ignore respectively. Then I could connect and run sudo dhcpcd wlan0 to get an IP address.

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